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333 lines
11 KiB
333 lines
11 KiB
//===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the Dwarf emissions parts of AsmPrinter.
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//
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//===----------------------------------------------------------------------===//
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#include "ByteStreamer.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/BinaryFormat/Dwarf.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/DIE.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCDwarf.h"
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#include "llvm/MC/MCRegisterInfo.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MachineLocation.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Target/TargetLoweringObjectFile.h"
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#include "llvm/Target/TargetMachine.h"
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#include <cstdint>
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using namespace llvm;
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#define DEBUG_TYPE "asm-printer"
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//===----------------------------------------------------------------------===//
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// Dwarf Emission Helper Routines
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//===----------------------------------------------------------------------===//
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/// EmitSLEB128 - emit the specified signed leb128 value.
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void AsmPrinter::emitSLEB128(int64_t Value, const char *Desc) const {
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if (isVerbose() && Desc)
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OutStreamer->AddComment(Desc);
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OutStreamer->emitSLEB128IntValue(Value);
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}
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void AsmPrinter::emitULEB128(uint64_t Value, const char *Desc,
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unsigned PadTo) const {
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if (isVerbose() && Desc)
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OutStreamer->AddComment(Desc);
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OutStreamer->emitULEB128IntValue(Value, PadTo);
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}
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/// Emit something like ".uleb128 Hi-Lo".
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void AsmPrinter::emitLabelDifferenceAsULEB128(const MCSymbol *Hi,
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const MCSymbol *Lo) const {
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OutStreamer->emitAbsoluteSymbolDiffAsULEB128(Hi, Lo);
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}
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static const char *DecodeDWARFEncoding(unsigned Encoding) {
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switch (Encoding) {
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case dwarf::DW_EH_PE_absptr:
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return "absptr";
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case dwarf::DW_EH_PE_omit:
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return "omit";
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case dwarf::DW_EH_PE_pcrel:
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return "pcrel";
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case dwarf::DW_EH_PE_uleb128:
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return "uleb128";
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case dwarf::DW_EH_PE_sleb128:
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return "sleb128";
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case dwarf::DW_EH_PE_udata4:
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return "udata4";
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case dwarf::DW_EH_PE_udata8:
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return "udata8";
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case dwarf::DW_EH_PE_sdata4:
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return "sdata4";
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case dwarf::DW_EH_PE_sdata8:
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return "sdata8";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
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return "pcrel udata4";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
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return "pcrel sdata4";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
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return "pcrel udata8";
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case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
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return "pcrel sdata8";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
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:
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return "indirect pcrel udata4";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
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:
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return "indirect pcrel sdata4";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
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:
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return "indirect pcrel udata8";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
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:
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return "indirect pcrel sdata8";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_datarel |
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dwarf::DW_EH_PE_sdata4:
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return "indirect datarel sdata4";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_datarel |
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dwarf::DW_EH_PE_sdata8:
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return "indirect datarel sdata8";
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}
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return "<unknown encoding>";
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}
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/// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
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/// encoding. If verbose assembly output is enabled, we output comments
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/// describing the encoding. Desc is an optional string saying what the
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/// encoding is specifying (e.g. "LSDA").
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void AsmPrinter::emitEncodingByte(unsigned Val, const char *Desc) const {
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if (isVerbose()) {
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if (Desc)
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OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
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Twine(DecodeDWARFEncoding(Val)));
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else
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OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
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}
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OutStreamer->emitIntValue(Val, 1);
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}
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/// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
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unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
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if (Encoding == dwarf::DW_EH_PE_omit)
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return 0;
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switch (Encoding & 0x07) {
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default:
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llvm_unreachable("Invalid encoded value.");
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case dwarf::DW_EH_PE_absptr:
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return MF->getDataLayout().getPointerSize();
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case dwarf::DW_EH_PE_udata2:
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return 2;
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case dwarf::DW_EH_PE_udata4:
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return 4;
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case dwarf::DW_EH_PE_udata8:
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return 8;
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}
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}
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void AsmPrinter::emitTTypeReference(const GlobalValue *GV, unsigned Encoding) {
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if (GV) {
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const TargetLoweringObjectFile &TLOF = getObjFileLowering();
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const MCExpr *Exp =
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TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);
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OutStreamer->emitValue(Exp, GetSizeOfEncodedValue(Encoding));
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} else
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OutStreamer->emitIntValue(0, GetSizeOfEncodedValue(Encoding));
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}
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void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
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bool ForceOffset) const {
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if (!ForceOffset) {
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// On COFF targets, we have to emit the special .secrel32 directive.
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if (MAI->needsDwarfSectionOffsetDirective()) {
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assert(!isDwarf64() &&
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"emitting DWARF64 is not implemented for COFF targets");
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OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
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return;
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}
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// If the format uses relocations with dwarf, refer to the symbol directly.
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if (MAI->doesDwarfUseRelocationsAcrossSections()) {
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OutStreamer->emitSymbolValue(Label, getDwarfOffsetByteSize());
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return;
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}
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}
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// Otherwise, emit it as a label difference from the start of the section.
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emitLabelDifference(Label, Label->getSection().getBeginSymbol(),
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getDwarfOffsetByteSize());
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}
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void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntry S) const {
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if (MAI->doesDwarfUseRelocationsAcrossSections()) {
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assert(S.Symbol && "No symbol available");
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emitDwarfSymbolReference(S.Symbol);
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return;
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}
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// Just emit the offset directly; no need for symbol math.
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OutStreamer->emitIntValue(S.Offset, getDwarfOffsetByteSize());
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}
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void AsmPrinter::emitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const {
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emitLabelPlusOffset(Label, Offset, getDwarfOffsetByteSize());
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}
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void AsmPrinter::emitDwarfLengthOrOffset(uint64_t Value) const {
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assert(isDwarf64() || Value <= UINT32_MAX);
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OutStreamer->emitIntValue(Value, getDwarfOffsetByteSize());
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}
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void AsmPrinter::maybeEmitDwarf64Mark() const {
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if (!isDwarf64())
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return;
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OutStreamer->AddComment("DWARF64 Mark");
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OutStreamer->emitInt32(dwarf::DW_LENGTH_DWARF64);
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}
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void AsmPrinter::emitDwarfUnitLength(uint64_t Length,
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const Twine &Comment) const {
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assert(isDwarf64() || Length <= dwarf::DW_LENGTH_lo_reserved);
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maybeEmitDwarf64Mark();
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OutStreamer->AddComment(Comment);
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OutStreamer->emitIntValue(Length, getDwarfOffsetByteSize());
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}
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void AsmPrinter::emitDwarfUnitLength(const MCSymbol *Hi, const MCSymbol *Lo,
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const Twine &Comment) const {
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maybeEmitDwarf64Mark();
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OutStreamer->AddComment(Comment);
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OutStreamer->emitAbsoluteSymbolDiff(Hi, Lo, getDwarfOffsetByteSize());
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}
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void AsmPrinter::emitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo,
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unsigned Encoding) const {
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// The least significant 3 bits specify the width of the encoding
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if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
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emitLabelDifferenceAsULEB128(Hi, Lo);
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else
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emitLabelDifference(Hi, Lo, GetSizeOfEncodedValue(Encoding));
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}
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void AsmPrinter::emitCallSiteValue(uint64_t Value, unsigned Encoding) const {
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// The least significant 3 bits specify the width of the encoding
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if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
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emitULEB128(Value);
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else
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OutStreamer->emitIntValue(Value, GetSizeOfEncodedValue(Encoding));
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}
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//===----------------------------------------------------------------------===//
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// Dwarf Lowering Routines
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//===----------------------------------------------------------------------===//
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void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
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switch (Inst.getOperation()) {
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default:
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llvm_unreachable("Unexpected instruction");
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case MCCFIInstruction::OpDefCfaOffset:
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OutStreamer->emitCFIDefCfaOffset(Inst.getOffset());
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break;
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case MCCFIInstruction::OpAdjustCfaOffset:
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OutStreamer->emitCFIAdjustCfaOffset(Inst.getOffset());
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break;
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case MCCFIInstruction::OpDefCfa:
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OutStreamer->emitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
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break;
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case MCCFIInstruction::OpDefCfaRegister:
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OutStreamer->emitCFIDefCfaRegister(Inst.getRegister());
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break;
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case MCCFIInstruction::OpOffset:
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OutStreamer->emitCFIOffset(Inst.getRegister(), Inst.getOffset());
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break;
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case MCCFIInstruction::OpRegister:
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OutStreamer->emitCFIRegister(Inst.getRegister(), Inst.getRegister2());
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break;
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case MCCFIInstruction::OpWindowSave:
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OutStreamer->emitCFIWindowSave();
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break;
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case MCCFIInstruction::OpNegateRAState:
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OutStreamer->emitCFINegateRAState();
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break;
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case MCCFIInstruction::OpSameValue:
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OutStreamer->emitCFISameValue(Inst.getRegister());
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break;
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case MCCFIInstruction::OpGnuArgsSize:
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OutStreamer->emitCFIGnuArgsSize(Inst.getOffset());
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break;
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case MCCFIInstruction::OpEscape:
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OutStreamer->AddComment(Inst.getComment());
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OutStreamer->emitCFIEscape(Inst.getValues());
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break;
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case MCCFIInstruction::OpRestore:
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OutStreamer->emitCFIRestore(Inst.getRegister());
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break;
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case MCCFIInstruction::OpUndefined:
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OutStreamer->emitCFIUndefined(Inst.getRegister());
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break;
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}
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}
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void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
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// Emit the code (index) for the abbreviation.
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if (isVerbose())
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OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
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Twine::utohexstr(Die.getOffset()) + ":0x" +
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Twine::utohexstr(Die.getSize()) + " " +
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dwarf::TagString(Die.getTag()));
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emitULEB128(Die.getAbbrevNumber());
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// Emit the DIE attribute values.
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for (const auto &V : Die.values()) {
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dwarf::Attribute Attr = V.getAttribute();
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assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
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if (isVerbose()) {
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OutStreamer->AddComment(dwarf::AttributeString(Attr));
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if (Attr == dwarf::DW_AT_accessibility)
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OutStreamer->AddComment(
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dwarf::AccessibilityString(V.getDIEInteger().getValue()));
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}
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// Emit an attribute using the defined form.
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V.emitValue(this);
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}
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// Emit the DIE children if any.
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if (Die.hasChildren()) {
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for (auto &Child : Die.children())
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emitDwarfDIE(Child);
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OutStreamer->AddComment("End Of Children Mark");
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emitInt8(0);
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}
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}
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void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
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// Emit the abbreviations code (base 1 index.)
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emitULEB128(Abbrev.getNumber(), "Abbreviation Code");
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// Emit the abbreviations data.
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Abbrev.Emit(this);
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}
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